"But what is really concerning to us, we have a series of very young men, who have very little prior conviction and they were dealing in drugs, and we will allege they were all carrying firearms whilst doing those drugs."

Some of the firearms arrive in Australia in parts, requiring assembly. There appeared to be no single point of entry or method of importation, she added.

Victoria's shootings include that of a 30-year-old man found dead in a targeted attack at Hampton Park in April. It came days after another man was shot dead in a suburban Melbourne park, with children finding two guns nearby the next day.

Police across the country are working together to tackle gun crime.

Crime Stoppers Victoria on Thursday launched the "Illegal guns affect everyone" campaign to try and reduce the number of unlicensed weapons.

"If someone you know has gone to the effort to get an illegal firearm, it is likely they will use it," Crime Stoppers chief executive Stella Smith said.

Information provided to the organisation in the past 12 months has helped remove 88 illegal guns from Victorian streets,including handguns, air rifles and crossbows.